California Code, Government Code - GOV § 51075

(a) “Open-space land” means any parcel or area of land or water which is essentially unimproved and devoted to an open-space use as defined in Section 65560 of the Government Code.

(b) “City” means any city or city and county.

(c) “Landowner” includes a lessee or trustee, if the expiration of the lease or trust occurs at a time later than the expiration of the open-space restriction or any extension thereof.

(d) “Open-space easement” means any right or interest in perpetuity or for a term of years in open-space land acquired by a county, city, or nonprofit organization pursuant to this chapter where the deed or other instrument granting such right or interest imposes restrictions which, through limitation of future use, will effectively preserve for public use or enjoyment the natural or scenic character of such open-space land.  An open-space easement shall contain a covenant with the county, city, or nonprofit organization running with the land, either in perpetuity or for a term of years, that the landowner shall not construct or permit the construction of improvements except those for which the right is expressly reserved in the instrument provided that such reservation would not be inconsistent with the purposes of this chapter and which would not be incompatible with maintaining and preserving the natural or scenic character of the land.  Any such convenant   1 shall not prohibit the construction of either public service facilities installed for the benefit of the land subject to such covenant or public service facilities installed pursuant to an authorization by the governing body of the county or city or the Public Utilities Commission.

(e) “Open-space plan” means the open-space element of a county or city general plan adopted by the local governing body pursuant to Section 65560 of the Government Code.

(f) “Nonprofit organization” means any organization qualifying under Section 501(c)(3) of the Internal Revenue Code in the preceding tax year, and which includes the preservation of open space as a stated purpose in its articles of incorporation.  Such qualification shall be demonstrated by a letter of determination from the Internal Revenue Service.